Table 5.

Dietary and food patterns and DR.

References	Study design	Purpose	Main findings
Dow et al. (70)	Systematic review	To identify, summarize and interpret the literature on the association between the diet and dietary intakes of specific foods, nutrients, and food groups, and the risk of diabetic retinopathy.	Adherence to the Mediterranean diet and high fruit, vegetable and fish intake may protect against the development of diabetic retinopathy, although the evidence is limited. Studies concerning other aspects of the diet are not in agreement. The role of the diet in the development of diabetic retinopathy is an area that warrants more attention.
Wong et al. (71)	Systematic review	To study the associations between dietary intake and DR, with the primary goal of providing a comprehensive assessment of the existing knowledge on the topic.	No significant associations of carbohydrate, vitamin D, and sodium intake with DR were found. Associations of antioxidants, fatty acids, proteins and alcohol with DR remain equivocal. Dietary fiber, oily fish, a Mediterranean diet and a reduced caloric intake are associated with lower risk of DR.
Francisco et al. (3)	Narrative review	To discuss the impact of dietary patterns on the incidence and progression of age-related eye diseases, namely age-related macular degeneration (AMD), cataracts, diabetic retinopathy, and glaucoma.	The authors found strong evidence about dietary patterns in regard to AMD and some in cataract, but there is surprisingly little conclusive evidence linking specific dietary patters with DR and glaucoma. Across studies looking at AMD progression, there are consensus findings that adherence to a prudent dietary pattern, the Mediterranean diet, and the healthy eating index all protect against AMD and that the western dietary pattern can accelerate AMD progression.
Ros et al. (72)	Narrative review	To focused on the latest findings concerning health effects of walnuts and ALA and relevant micronutrients.	Walnuts have a high content of fiber, polyphenols, phytosterols, gamma-tocopherol, and mainly linolenic acid (ALA), as well as various minerals, which confer antioxidant, anti-inflammatory, cardio- and neuro-protective, antithrombotic, antiarrhythmic, hypocholesterolemic properties and regulation of the intestinal microbiota
Poulose et al. (73)	Narrative review	To review evidences for the beneficial effects of consuming a walnut-rich diet.	Polyphenolic compounds found in walnuts not only reduce the oxidant and inflammatory load on brain cells but also improve interneuronal signaling, increase neurogenesis, and enhance sequestration of insoluble toxic protein aggregates.
Valero-Vello et al. (74)	Systematic review	To identify he role of diet and nutrition in the eyes and vision, and the potential antioxidant, anti-inflammatory and neuroprotective effects of natural food (broccoli, saffron, tigernuts and walnuts), the MD and nutraceutic for patients at risk of vision loss.	Nut-enriched diet bring benefits in ocular diseases, such as glaucoma, DR and degenerative maculopathy, chronic pathologies of a degenerative nature for the ocular structures, which have common pathophysiological mechanisms, related precisely to oxidative stress and inflammation
Meng et al. (75)	Systematic review	To summarize and discusses the effects of tea against diabetes mellitus and its complications based on the findings from epidemiological, experimental, and clinical studies, with the special attention paid to the mechanisms of action.	Epidemiological studies found that drinking tea could reduce the risk of diabetes mellitus and diabetic complications. In addition, experimental studies have shown that tea could protect against diabetes mellitus and diabetic complications by improving insulin resistance, activating the insulin signaling pathway, playing an insulin-like role, improving oxidative stress, and alleviating inflammatory response. Further, tea has synergistic effects with certain antidiabetic drugs. Tea has been observed to act as a potent neuroprotector in the retina.
Natella et al. (76)	Narrative review	To examine the possibility that the pattern of coffee consumption could influence risk of type 2 diabetes, and to evaluate the possible relationship between coffee consumption and other risk factors associated with diabetes.	The studies conducted thus far provide a clear indication that healthy, habitual coffee drinkers are more protected from the risk of contracting diabetes than individuals who do not drink coffee. Long-term consumption of coffee is able to reduce oxidative stress. This could be due to the caffeine itself, which is considered an antioxidant, but also to other coffee components,
Akash et al. (77)	Narrative review	To explore and summarize the scientific literature on the potential effects of coffee consumption on T2DM.	Coffee may directly affect different mechanistic factors that are involved in the pathogenesis of T2DM. Several components of coffee may ameliorate the symptoms of T2DM by affecting glucose regulation. These may include the effects of CGA on glucose-6-phosphatase, the antioxidant activity of polyphenols on α-glucosidase, and the effects of caffeine on insulin secretion.
Carlström et al. (78)	Meta-analyses of observational studies	To cover current knowledge regarding the effects of coffee consumption on development of T2D or modulation of adverse complications. Moreover, bioactive components in coffee, polymorphisms, and potential underlying mechanisms in relation to T2D and adverse complications are discussed.	Available evidence indicates that coffee consumption is inversely associated with risk of T2D. Possible mechanisms behind this association include thermogenic, antioxidative, and anti-inflammatory effects; modulation of adenosine receptor signaling; and microbiome content and diversity.